Disclosure of Invention
In order to overcome the technical defects that the content of chitosan oligosaccharide in a finished product is difficult to quantify and the operation technology is complicated in the prior art, the invention provides the method for accurately measuring the content of the chitosan oligosaccharide by the resonance Rayleigh scattering method. The resonance Rayleigh scattering method for measuring the chitosan oligosaccharide is established by taking the linear relation between the resonance scattering intensity and the chitosan oligosaccharide in a certain concentration range as the quantitative basis of the chitosan oligosaccharide. The method is influenced by ion concentration and interferents, and in the actual sample measurement, a standard substance with the ion concentration of 0.05-0.20 mol/L needs to be controlled to serve as a quantitative standard, so that the method has the advantages of low reagent price, high sensitivity, good reproducibility, simplicity and convenience in operation and the like.
A method for accurately measuring the content of chitosan oligosaccharide by a resonance Rayleigh scattering method comprises the following steps:
1) drawing a standard curve of delta I and chitosan oligosaccharide with different concentrations
Adding 1.0mL of B-R buffer solution, a chitosan oligosaccharide standard solution with a certain concentration gradient, 1.0mL of sensitizer with the concentration of 0.086mol/L and 1.0mL of sensitizer with the concentration of 1.0 multiplied by 10 into a 10mL colorimetric tube-4Adding distilled water to desired volume, shaking thoroughly, placing at room temperature for 10min, and placing on F-2500 type fluorescence spectrophotometer at lambdaex=λemSynchronous scanning is carried out, and the resonance scattering intensity I of each detection system containing the chitosan oligosaccharide at the position of lambda-470 nm is recorded, wherein the resonance scattering intensity I of the system of a reagent blank at the position of lambda-470 nm is recorded0And calculating the value of Delta I ═ I-I0Establishing a standard curve C of the delta I and the concentration of the chitosan oligosaccharide;
2) preparation of 10. mu.g/mL sample working solution: removing the capsule shell of the chitosan oligosaccharide capsule, weighing 0.04g of the chitosan oligosaccharide capsule into a 100mL volumetric flask, dissolving the chitosan oligosaccharide capsule in 0.5mol/L glacial acetic acid, and fixing the volume to obtain a sample stock solution. Filtering the stock solution with absorbent cotton in a funnel, centrifuging the filtrate for 20min at 6000r/min by a centrifuge, taking 2.5mL of supernatant in a 100mL volumetric flask, and performing constant volume to obtain a sample working solution with the concentration of 10 mug/mL.
3) Determination of the content of chitosan oligosaccharide in the sample: sampling 1mL of working solution, measuring according to the detection method in the step 1), measuring the scattering value I at 470nm, and calculating delta I-I0Substituting the delta I into a linear regression equation to obtain the content of the chitosan oligosaccharide in the sample, and simultaneously performing a standard addition recovery test.
The method for accurately measuring the content of the chitosan oligosaccharide by the resonance Rayleigh scattering method is characterized in that the B-R buffer solution is prepared by 0.04mol/L mixed acid and 0.2mol/L NaOH solution according to different proportions.
The method for accurately measuring the content of the chitosan oligosaccharide by the resonance Rayleigh scattering method is characterized in that the mixed acid is prepared from orthophosphoric acid, glacial acetic acid and boric acid according to different proportions.
The method for accurately measuring the content of the chitosan oligosaccharide by the resonance Rayleigh scattering method has the advantages that the pH value of the B-R buffer solution is 4.9.
In the method for accurately determining the content of the chitosan oligosaccharide by the resonance Rayleigh scattering method, the sensitizer is one of Tween 20, Tween 80, OP emulsifier, sodium dodecyl sulfate or sodium dodecyl sulfate
In the method for accurately determining the content of the chitosan oligosaccharide by the resonance Rayleigh scattering method, the sensitizer is sodium dodecyl sulfate.
In the method for accurately measuring the content of the chitosan oligosaccharide by the resonance Rayleigh scattering method, the adding sequence of the solution in the step 1 is that the ruby red solution is firstly added, then the sodium dodecyl sulfate solution is added, the RB buffer solution is added again, and finally the chitosan oligosaccharide solution is added.
The method for accurately measuring the content of the chitosan oligosaccharide by the resonance Rayleigh scattering method has the concentration range of the chitosan oligosaccharide of 0.5 mu g/mL-2.5 mu g/mL.
Sample pretreatment: removing the capsule shell of the chitosan oligosaccharide capsule, weighing 0.04g of the chitosan oligosaccharide capsule into a 100mL volumetric flask, dissolving the chitosan oligosaccharide capsule in 0.5mol/L glacial acetic acid, and fixing the volume to obtain a sample stock solution. Filtering the stock solution with absorbent cotton in a funnel, centrifuging the filtrate for 20min at 6000r/min by a centrifuge, taking 2.5mL of supernatant in a 100mL volumetric flask, and performing constant volume to obtain a sample working solution with the concentration of 10 mug/mL.
Sampling 1mL of working solution, measuring according to an experimental method, measuring the absorbance value I at 470nm, and calculating delta I-I0Substituting the delta I into a linear regression equation to obtain the content of the chitosan oligosaccharide in the sample, and simultaneously performing a standard addition recovery test.
Test example:
1. resonance Rayleigh scattering spectrum of chitosan oligosaccharide-ruby red-sodium dodecyl sulfate system
FIG. 1 is a resonance scattering spectrum of the system. As can be seen from fig. 1, the scattering values of COS, SDS and ruby red themselves are low, but the scattering value is significantly increased when COS is combined with all three of ruby red and SDS, and there is a scattering peak at 470 nm. The blank group of the experiment has a lower scattering value, and the experimental group increases the scattering value of the system along with the increase of the concentration of COS, so that a better linear relation exists.
Effect of the pH of the BR buffer solution on the Scattering value of the System
To a 10mL cuvette, 2.0mL of a buffer solution B-R having a pH of 3, 4, 5, 6, 1.0mL of a 10. mu.g/mL chitosan oligosaccharide solution, and 2.0mL of a 1.0X 10 solution were added-4And (3) fixing the volume of the ruby red solution of mol/L to a scale with triple distilled water, fully shaking up, oscillating for 90s, and standing at normal temperature for 30 min. On a F-2500 type spectrofluorometer with a lambdaex=λemAnd carrying out synchronous scanning to obtain a resonance Rayleigh scattering spectrum.
As a result, as shown in fig. 2 and fig. 3, the acidity of the buffer solution has a significant influence on the reaction system, and the scattering value is large at around pH 5.0, and the final optimum acidity condition is determined at pH 4.9 by a refinement experiment of acidity.
3. Effect of different buffers on the Scattering value of the System
The influence of 3 buffer solutions, namely B-R buffer solution, citric acid-sodium citrate buffer solution and glycine-hydrochloric acid buffer solution, on the scattering value of the system is respectively examined. The scattering values of the respective buffer solutions were obtained by changing the buffer solution added according to the experimental method.
As shown in FIGS. 2, 4 and 5, the system has the highest sensitivity and the largest scattering value in the B-R buffer solution, so the best buffer solution is selected as the B-R buffer solution.
4. Effect of buffer addition on Scattering values
The buffer solution provides an appropriate acidity binding environment for the experimental system, the addition amount of the buffer solution has certain influence on the formation of the ionic associate, other experimental conditions are not changed, the addition amount of the B-R buffer solution with the pH of 4.9 is changed to 0.5, 1.0, 1.5, 2.0, 2.5 and 3mL, and the scattering value is measured.
As a result, as shown in FIG. 6, the B-R buffer solution added in an amount of 1.5mL and 2.5mL showed peaks, and the Δ I was larger at 1.5mL, so that the B-R buffer solution was added in an amount of 1.5 mL.
5. Effect of Gem Red addition on Scattering values
Geranium red as a dye probe is combined with target substance chitosan oligosaccharide, the addition amount of the Geranium red directly influences the formation of ion association, other experimental conditions are not changed, and the concentration is changed to be 1.0 multiplied by 10-4The amount of ruby red added was 0.5, 1.0, 1.5, 2.0, 2.5, 3mL in mol/L, and the scattering value was measured.
The results are shown in fig. 7, where the amount of ruby red added has a significant effect on the reaction system, and it can be seen that as the ruby red dye solution is added, Δ I rises first and then falls, and peaks at an addition of 2 mL. Therefore, the adding amount of the ruby red is 2 mL.
6. Influence of sensitizer addition on Scattering values
The influence of 5 surfactants including Tween 20, Tween 80, OP emulsifier, Sodium Dodecyl Sulfate (SDS) and sodium dodecyl sulfate (SLS) on the scattering value of the system is examined. According to the experimental method, other experimental conditions are not changed, and finally 1mL of surfactant is added, one group is kept stand at normal temperature, the other group is heated in a water bath at 80 ℃ for 10min and then kept stand to normal temperature, and the scattering value is measured.
The results are shown in fig. 8, when sodium dodecyl sulfate is added, the scattering value of the system is obviously enhanced, and the results show that the adding amount of the sodium dodecyl sulfate has certain influence on the system, so the Sodium Dodecyl Sulfate (SDS) flushing solution is selected as the sensitizer for the experiment.
7. Effect of sodium dodecyl sulfate addition on Scattering values
Sodium dodecyl sulfate is an anionic surfactant, the critical micelle concentration of the surfactant is 0.0086mol/L, and when the Critical Micelle Concentration (CMC) is reached, surfactant molecules are mutually aggregated by van der Waals force to form micelles with oleophilic groups inward and hydrophilic groups outward, so that the solubility of ion associations in a micelle solution is remarkably increased, and the resonance scattering strength is remarkably increased by the generated micelle solubilization. The scattering values were determined by changing the amount of sodium lauryl sulfate added at a concentration of 0.086mol/L to 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3mL without changing other experimental conditions.
The result is shown in fig. 9, and the result shows that the addition of sodium dodecyl sulfate has a certain influence on the system, the overall trend is increased first and then decreased, the scattering value is maximum when the addition is 1mL, and then slightly decreased, the scattering value is larger when the addition is 1.0mL, and the stability of the system is good, so that the optimal addition of 0.086mol/L sodium dodecyl sulfate is 1.0mL, namely, the corresponding concentration of sodium dodecyl sulfate is 0.0086 mol/L.
8. Effect of the order of reagent addition on the Scattering value of the System
Under experimental conditions, the influence of 12 different adding sequences of anionic dyes ruby red, B-R buffer solution, COS and SDS on the sensitivity of the system is examined. The results are shown in Table 1, FIG. 10, and the optimal sequence of addition is "Gem Red + SDS + RB buffer + COS", where the system has the highest scattering values, the highest sensitivity and the best reproducibility.
TABLE 1 Effect of the order of addition
9. Influence of reaction temperature on the scattering value of the System
Under experimental conditions, the influence of different temperatures of 20-100 ℃ on the sensitivity of the system is examined, the result is shown in FIG. 11, and the result shows that the temperature has influence on the scattering value of the system. The scattering value is in the trend of rising first, then falling and then rising along with the rising of the temperature, the maximum scattering value is reached at 20 ℃, and the repeatability is better at the reaction temperature, so the optimal temperature of the system is 20 ℃.
10. Effect of the settling time on the Scattering value of the System
And under the better condition, the stable time of the system is inspected, the stable time is inspected for 3h, and the scattering value is measured at intervals. The result shows that the system can reach stability and the scattering value reaches the maximum within 10min, and the stable scattering value can be kept unchanged within 2 h. Therefore, the stabilization time was selected to be 2 h.
11. Effect of ion intensity on the Scattering value of the System
And (3) examining the influence of the ionic strength on the scattering value of the system by using NaCl (0.005-0.3 mol/L). As a result, as shown in FIG. 12, the ion concentration was in the range of 0.05mol/L to 0.2mol/L, the scattering value tended to be stable, and the system was relatively stable.
12. Effect of coexisting materials on the Scattering value of the System
The interference of 6 coexisting substances on the system is examined, and the concentration of the chitosan oligosaccharide in the system is 1 mug/mL. The allowable amounts of the respective coexisting materials within. + -. 5% relative errors are shown in Table 2. The interference of common copper, calcium, manganese and the like is small, and the allowable amount is large.
TABLE 2 Effect of coexisting materials
Compared with the prior art, the invention has the following technical advantages:
1) good linearity and low detection limit: under the best experimental condition, the corresponding delta I of the chitosan oligosaccharide with different concentrations is measured according to the experimental method, a standard curve is drawn, and the result shows that the chitosan oligosaccharide has good linear relation with the delta I within the range of 0.5 mu g/mL-2.5 mu g/mL, the linear range is wide, and the detection limit is 0.4708 mu g/mL.
2) The method is influenced by ion concentration and interferents, and in the actual sample measurement, a standard substance with the ion concentration of 0.05-0.20 mol/L needs to be controlled to serve as a quantitative standard, so that the method has the advantages of low reagent price, high sensitivity, good reproducibility, simplicity and convenience in operation and the like.
Detailed Description
The invention is further described below by means of specific examples, but said invention is not in any way restricted to the scope of the invention as claimed.
Examples
A method for accurately measuring the content of chitosan oligosaccharide by a resonance Rayleigh scattering method comprises the following steps:
1) drawing a standard curve of delta I and chitosan oligosaccharide with different concentrations
Adding 1.0mL of B-R buffer solution with pH of 4.9, a chitosan oligosaccharide standard solution with a concentration gradient, 1.0mL of sodium dodecyl sulfate solution with concentration of 0.086mol/L and 1.0mL of sodium dodecyl sulfate solution with concentration of 1.0 multiplied by 10 into a 10mL colorimetric tube-4Adding distilled water to desired volume, shaking thoroughly, placing at room temperature for 10min, and placing on F-2500 type fluorescence spectrophotometer at lambdaex=λemSynchronous scanning is carried out, and the resonance scattering intensity I of each detection system containing the chitosan oligosaccharide at the position of lambda-470 nm is recorded, wherein the resonance scattering intensity I of the system of a reagent blank at the position of lambda-470 nm is recorded0And calculating the value of Delta I ═ I-I0And establishing a standard curve C of the delta I and the concentration of the chitosan oligosaccharide.
2) Preparation of 10. mu.g/mL sample working solution: removing the capsule shell of the chitosan oligosaccharide capsule, weighing 0.04g of the chitosan oligosaccharide capsule into a 100mL volumetric flask, dissolving the chitosan oligosaccharide capsule in 0.5mol/L glacial acetic acid, and fixing the volume to obtain a sample stock solution. Filtering the stock solution with absorbent cotton in a funnel, centrifuging the filtrate for 20min at 6000r/min by a centrifuge, taking 2.5mL of supernatant in a 100mL volumetric flask, and performing constant volume to obtain a sample working solution with the concentration of 10 mug/mL.
And (3) drawing a sample curve by using the sample working solution according to an experimental method, and comparing the sample curve with a chitosan oligosaccharide standard curve to obtain a linear regression equation of the sample, wherein the linear regression equation is that delta I is 33.31c +151.41, and the correlation coefficient is 0.9901.
3) Determination of the content of chitosan oligosaccharide in the sample: sampling 1mL of working solution, measuring according to the detection method in the step 1), measuring the scattering value I at 470nm, and calculating delta I-I0Substituting the delta I into a linear regression equation to obtain the content of the chitosan oligosaccharide in the sample, and simultaneously performing a standard addition recovery test.
Sampling 1mL of working solution, measuring according to an experimental method, measuring a scattering value I at 470nm, and calculating delta I-I0Substituting the delta I into a linear regression equation to obtain the content of the chitosan oligosaccharide in the sample, and simultaneously performing a standard addition recovery test. The results were: the content of the chitosan oligosaccharide in the olygoxate chitosan oligosaccharide capsule is 1174mg/g, and the RSD is 2.081%. The recovery rates are shown in Table 3.
TABLE 3 results of sample analysis
In the experiment, 2.0mL of colorimetric tubes with a concentration of 1.0X 10 were sequentially added-4Ruby red in mol/L, sodium lauryl sulfate in 1.0mL at a concentration of 0.086mol/L, B-R buffer solution in 1.5mL at pH 4.9, and 10. mu.g in 3.0mLAnd (3) diluting the chitosan oligosaccharide solution to a certain volume by using distilled water, fully shaking up, and standing for 10min at room temperature. On a F-2500 type fluorescence spectrophotometer, as lambdaex=λemSynchronous scanning is carried out, and the determination is completed within 2 h. Recording the resonance scattering intensity I of the chitosan oligosaccharide-containing system at λ 470nm, wherein the resonance scattering intensity I of the reagent blank system at λ 470nm0And calculating the value of Delta I ═ I-I0. The chitosan oligosaccharide has good linear relation with Delta I within the concentration range of 0.5 mu g/mL-2.5 mu g/mL, the linear range is wide, and the detection limit is 0.4708 mu g/mL. The method is influenced by ion concentration and interferents, and in the actual sample measurement, a standard substance with the ion concentration of 0.05-0.20 mol/L needs to be controlled to serve as a quantitative standard, so that the method has the advantages of low reagent price, high sensitivity, good reproducibility, simplicity and convenience in operation and the like.
Linear range and detection limit
Under the best experimental conditions, the corresponding delta I of chitosan oligosaccharide with different concentrations is determined according to an experimental method, a standard curve is drawn, the result shows that the chitosan oligosaccharide has a good linear relation with the delta I in the concentration range of 0.5 mu g/mL-2.5 mu g/mL, the linear regression equation is that the delta I is 33.31c +151.41, the correlation coefficient is 0.9901, the method linear range is wide, and the detection limit is 0.4708 mu g/mL.